New to towing vehicle with E-Z Pass question

First set up an ordinary NY E-ZPass account, just as you would for any passenger vehicle. Then go to this link and follow the instructions for the "Thruway Motorhome Discount Plan". There's a link where the needed form can be downloaded and printed out. E-ZPass will send you the proper tag for your motorhome toad combination, and the standard tag gets put in a shielded bag or wrapped in foil while the towing tag is in use.